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E46 (1999 - 2006) The fourth generation 3 Series (E46 chassis) was introduced in 1999 and set the standard for engineering and performance during it's years of production including being named to Car & Driver's 10 best list every one of those years! ! -- View the E46 Wiki

My engine light is on for a few days and off for a day and on again etc. At first I thought it may have to do with the cold weather because each time it was off, the temp was 70 or better. But since the temp here in Houston have been consistently in the 60's I didn't think it has to do with the temp anymore.

I brought the car to Autozone to read and it said the precat sensor, I took my car to an Indy and he told me he's not sure and it could be $1400 or more since there is "obvious attempt to fix this, based on the wrench marks on the part blah blah" but he test drove the car and he said everything is normal. So, I took the car and left and it's been a few weeks but the light stayed on permanent now.

The car is operating normally. I get 23 MPG and I notice no adversed effects in the performance.

My questions then:

Could it be possible that a wire is loose somewhere that causes the SES light to be on?

If indeed the precat sensor is going, can I continue to drive until it's gone then replace?

Where else could I look to solve this?

While I'm asking for help I may ask this question as well, my car is a 04 but only has 34k
on it. Should I change out the spark plugs?

The tool easily connects to your diagnostic port in the engine bay and allows you to read any codes for a check engine light as well reset your oil service and inspection light with the push of a button.

This tool is a must for the first time do-it-yourself mechanic and to complete any tool box.